Large marine shackle assemblies are used by military and commercial crew members for coupling chains, buoys, and other objects. An example of such a shackle assembly 2 is illustrated with respect to FIGS. 1A-C. A shackle assembly 2 includes a shackle 4, a bolt 6, and a split key 8.
In an exemplary embodiment shackle 4 is U-shaped with a closed curved end 10 from which two shackle legs 12 extend. The two legs have axially aligned cylindrical openings 14. The bolt 6 includes a head 16 and a shaft 18 extending from the head 16. Shaft 18 also has a rectangular vertical slot 20 formed therethrough and centered upon a diameter of shaft 18. The split key 8 has a enlarged rounded end 22 from which two split key legs 24 extend.
Comparing FIGS. 1A and 1B, the shaft 18 of the bolt 6 is received through the axially aligned cylindrical openings 14 in order to close shackle 4. The shaft 18 is secured in a position that closes shackle 4 by passing the split key legs 24 of split key 8 through vertical slot 20 of bolt 6 and then bending the legs away from one another as depicted in FIG. 1C.
In practice this procedure is difficult. For large marine applications the shaft 18 can be over two inches in diameter. A hammer is typically used or required to bend the split key into the configuration shown in FIG. 1C. It is challenging to hold the split key 8 in its proper position and then to obtain the proper angle between key legs 24. Each leg needs to be bent by an angle in the range of about 40-50 degrees in order for this procedure to be effective. If the angle is too small the split key 8 may fall out during use. If the angle is too large the split key 8 may fail due to excessive bending stress. Also, too large of an angle will make the later removal of split key 8 difficult. Finally, the process of bending split key 8 can be a time consuming and difficult process. There is a need to improve the speed and accuracy of installing split keys 8.